OneNote Files From Locally stored to Cloud, and Back to Local Storage

OneNote for Office 365 has the capacity to store the Notebook locally. 

For a locally stored notebook, to be shared one can do the following:

Open the locally stored notebook in OneNote for Windows 10. It will automatically sync up to OneNote on the web.

At some point, you may want to be able to create a backup of this: Open OneNote for Office 365, go to File | Open | Sign In, then Search for the Notebook. Once it is open, go to File | Export | Notebook, select OneNote Package (*.onepkg). Store that to a location. You can then open it with OneNote 365.